Argon has become an increasingly important component in the metallurgical industry. Argon degassing of stainless and specialty steels is an example of the application of argon in the iron and steel industry. Argon is also used extensively in the cutting and welding of various metals. The development of the plasma jet torch has permitted the use of argon mixtures heated to very high temperatures to be used for cutting operations and for coating metals with refractory materials. More recently argon has become an important ingredient in the electronics industry as a carrier, purge, or blanketing gas to exclude air from certain processes, especially in growing crystals, ion milling, and other etching processes.
Argon is generally produced using an argon sidearm column which receives a feed stream from the lower pressure column of a double column cryogenic air separation plant. This arrangement enables the production of a crude argon product which is then passed through a deoxo unit to produce high purity argon.
A recent advancement in the field of argon production has been the use of a superstaged argon sidearm column which can produce high purity argon without the need for processing through a deoxo unit. However, such a superstaged sidearm column is expensive to build and to maintain.
Accordingly, it is an object of this invention to provide a cryogenic rectification system for the production of argon which can produce relatively high purity argon without the need for a superstaged argon sidearm column.